ISTANBUL - A remote-controlled bomb injured 15 police officers and one civilian on Thursday as the blast hit a police minibus passing close to the Istanbul headquarters of Turkey's ruling AK Party, police said.Kurdish separatists, Islamist militants - including al-Qaida - as well as groups on the far left and right have all carried out bomb attacks in Turkey, but there was no immediate claim of responsibility and officials said it was too early to say who could be behind the blast."As a police vehicle carrying 21 officers was passing by, a remote control bomb on a motorcycle exploded. Our teams are carrying out the investigation," Istanbul police chief Huseyin Capkin told reporters.Prime Minister Tayyip Erdogan strongly condemned the attack in Istanbul's Sutluce district, a poor, but developing neighborhood on the banks of the Golden Horn inlet."Our struggle against terrorism will continue with the utmost determination," he told a news conference in Ankara.One local shopkeeper, Orhan, said he ran out of his shop when he heard the explosion around 9 am. "People ran to the minibus. There were no flames. The injured were moved to a building nearby and later into the ambulances."Security guards from nearby offices and passers-by helped move the wounded to a building housing the Independent Industrialists and Businessmen's Association (MUSIAD), a conservative business group close to the government whose headquarters are next door to the AK Party building."We were afraid the bomb had hit our building because the blast was so loud," MUSIAD spokesman Sadi Dinleyici told CNN Turk. "Windows were broken and the wounded police officers were given first aid in our building."Fire engines and police vehicles surrounded the area and glass littered the streets as forensic officers in white overalls combed the area for evidence.Istanbul Governor Huseyin Avni Mutlu, when asked if the attack could have been carried out by Kurdistan Workers Party (PKK) militants, said: "It is too early to say". He added that it was not an attack on either the AK Party or MUSIAD."It was a direct attack on our police forces ... it was an explosion that had nothing to do with either the civil society group MUSIAD or the party. It was a police vehicle on its way somewhere else," he said.Workers arriving at a nearby building site had earlier moved the motorcycle as it was blocking their way, media reported.